A unified microscopic mechanism for donor deactivation in Si

Dopant atoms segregate to SiO2/Si(001) interfaces. This causes problems dur ing manufacture of submicron microelectronic devices. On the basis of ab in itio calculations, we identify the mechanisms by which P atoms are bonded a nd deactivated under the interface. We argue that P segregation occurs by ( 1) trapping at interfacial dangling bonds, (2) trapping at vacancies and va cancy-oxygen complexes bound under the interface, and (3) formation of pair s of threefold-coordinated P atoms. The first mechanism is important at low dopant concentrations and when no vacancies are available, the second one dominates at medium dopant concentrations after P implantation, the third o ne controls the segregation at dopant concentrations around 10(19) cm(-3) o r higher. (C) 1999 Elsevier Science B.V. All rights reserved.